Device and Method for Transforming a Metal Slab from Coil Configuration into Sheet Configuration

ABSTRACT

The present invention relates to a device for transforming a metal slab from coil configuration into sheet configuration, subsequently comprising: a rotatable coil holder ( 21 ); at least one align unit; and a separator; wherein the rotatable coil holder, the at least one align unit and the separator are placed in line wherein the rotatable coil holder is provided with at least one air knife ( 22 ) that directs an air flow onto the width of the metal slab. The present invention also relates to a method for transforming a metal slab from coil configuration into sheet configuration, comprising the method steps: A) placing a metal slab coil on a rotatable coil holder; B) rotating the metal slab coil and unwinding the coil; C) feeding the unwound metal slab through at least one at align unit; and D) separating individual metal slab sheets wherein an air knife is directs an air flow onto the width of the metal slab before the unwound metal slab is fed through an align unit.

The present invention relates to a device for transforming metal slabfrom coil configuration into sheet configuration, subsequentlycomprising: a rotatable coil holder; at least one align unit; aseparator; and a stacking unit; wherein the rotatable coil holder, theat least one align unit, the separator and the stacking unit are placedin line. The present invention also relates to a method for transforminga metal slab from coil configuration into sheet configuration,comprising the method steps: A) placing a metal slab coil on a rotatablecoil holder; B) rotating the metal slab coil and unwinding the coil; C)feeding the unwound metal slab through at least one at align unit; andD) separating individual metal slab sheets.

In the metal production industry use is made of flat metal sheetmaterial. Typically the sheet metal material is manufactured, shippedand stored in large diameter slab coils (rolls) with weights up to tensof tons to optimise production. Before further use of the material thecoiled slab may be transformed into flat sheet configuration. Suchprocessing of a coiled slab is also referred to as “decoiling” andinvolves unwinding the coiled slab and subsequently feeding the unwoundmetal slab through one or more roll-forming units after the passage ofwhich usually the unwound flat slab is split up in individual metalsheets of adjustable length. The decoiling takes place in a productionline of considerable length wherein also other operations may beperformed such as for instance edge trimming, stress relievingoperations, slitting and stacking. A typical—but notlimitative—decoil-line involves the subsequent processing steps of:unwinding; pre-aligning; first aligning; second aligning and cutting.The decoiling of metals slab thus results in the transformation of acoiled slab into flat sheets of adjustable size and is suited for thetransformation of various types of coils, like for instance process hotrolled coils, pickled and oiled coils and tear drop steel coils.

A problem that may arise in the transformation of coiled slab into flatsheet configuration is that the resulting surface quality of the flatsheets is negatively influenced by the transformation process.

The object of the present invention is to provide an improved method andan improved device for transforming a metal slab from coil configurationinto sheet configuration wherein the surface quality is more positivelyinfluenced than it is influenced by the transformation process accordingthe prior art.

The invention provides for this purpose a device for transforming metalslab from coil configuration into sheet configuration, subsequentlycomprising: a rotatable coil holder; at least one align unit and aseparator; wherein the rotatable coil holder, the at least one alignunit, the separator and the stacking unit are placed in line, andwherein the rotatable coil holder is provided with at least one airknife that directs an air flow onto the width of the metal slab. Due tothe air knife acting onto the metal slab before the first aligning ofthe slab takes place the metal slab will at least partly be stripped ofpollutants like for instance pollutants shaped as powder, loose or moreor less attached parts and/or plates, stains, inorganic contaminants,rust or scale. These pollutants may for instance be liquid (water)and/or other non-metal pollutants as well as pollutants originating fromthe metal slab or oxides of the metal slab. The removal of thepollutants using the air knife makes that the pollutants are notinfluencing the surface quality of the metal slab in an alignment unitwhich results in a higher surface quality grade of the sheetconfiguration metal slab after transformation process than the surfacequality of the transformed metal slab according the prior art. Thehigher surface quality grade may be realised due to the fact that lesspollutants are present during the first aligning, during which aligningprocess at least local pressure is exerted on the metal slab. The airknife may be directed to the metal slab at a location where the metalslab is still on the coil or may be directed onto the metal slab shortlyafter the slab has been fed away (thus being unwound) from the coil. Thedevice according the present invention may also be provided with one ormore brushes for further cleaning of the metal slab, which brushes maycooperate with the air knife to further enhance the combined cleaningeffect.

In an embodiment the device may also comprise a stacking unit placed inline with the rotatable coil holder, the at least one align unit and theseparator. After the metal slab from coil configuration is configured inseparated flat sheets of metal slab the sheets have to be processedfurther. As normally the transforming device is not coupled with asubsequent sheet processing unit, the metal sheets have to betransported from the transforming device to another location where asubsequent sheet processing takes place. Stacking of the metals sheetsmay enable economic transportation of the sheets.

In a further embodiment of the device according the present inventionthe air knife may comprise an air feed and a nozzle with a width of atleast the width of the metal slab coil to be transformed. Such a nozzleenables the removal of pollutants over the complete width of the metalslab. To provide the air flow the air knife may also be provided withone or more fans, for instance a blower. A typical seize of the nozzleaperture is 2000*1 mm, or more than 1500 mm, and a typical air speed ofthe air knife may be 100-200 m/s, for instance 150 m/s. In case the airknife is provided with at least one heater the air blown to the metalslab may be heated, which may for instance be helpful in case the metalslab contains liquid residue. Such an air heater may for instance beembodied as an electric heating coil.

To enable control of the intensity of the air flow contacting the metalslab the nozzle of the air knife may be mounted on a nozzle carrier thatis moveable relative to the rotatable coil holder. Such moveable holderenables to control the distance of the nozzle to the metal slab and thusalso the intensity of the air flow contacting the metal slab. The nozzlecarrier may be provided with bias means and at least one stop directedtowards the rotatable coil holder to contact the outside of the metalslab coil. In such configuration the distance of the nozzle of the airknife to the outside of the coil is constant as the nozzle is urged tothe metal slab and the stop makes that the nozzle is always as close aspossible to the metal slab independent on the diameter change of themetal slab coil dependent on the status of unwinding of the remainingpart of the metal slab coil. The stop may be embodied as one or morewheels or rollers. With for instance the use of a balance weight thenozzle carrier may be urged against the outside of the metal slab coilwith a constant pressure. Furthermore it is an option to connect thenozzle carrier pivotable (swivelling) to the rotatable coil holder sothat the distance of the nozzle to the metal slab is to control with asimple construction that may utilize gravitation to at least partiallydrive the displacement of the nozzle carrier. However also alternativebias means may be used, like for instance various types of springs orcylinders that may urge the nozzle carrier with a constant pressureagainst the outside of the metal slab coil. It is also possible to drivethe movement of the nozzle carrier in different direction with differentmeans; for instance to make the nozzle carrier to follow the decreasingdiameter from the outside of the remaining metal coil by gravity and tomake the return movement (away from the coil) by a (hydraulic ofpneumatic) cylinder. To further enhance the control of the distance ofthe nozzle to the metal slab also an electronic control system may beprovided.

In yet a further embodiment of the device according the presentinvention parallel to the air knife a subsidiary air blower may besituated. Such subsidiary air blower may for instance comprise at leastone air blower fan, an air blower feed and an air blower nozzle with awide of at least the width of the metal slab coil to be transformed.

Also the air knife may be provided with at least one inlet for theextraction of air. Loose pollutants due to the activity of the air knifeacting on the metal slab may be removed (sucked away) from thetransforming device preventing precipitation of the pollutants atlocations where it may have a negative effect for the equipment and/orthe processing quality.

The present invention also provides a method for transforming a metalslab from coil configuration into sheet configuration, comprising themethod steps: A) placing a metal slab coil on a rotatable coil holder;B) rotating the metal slab coil and unwinding the coil; C) feeding theunwound metal slab through at least one at align unit; and D) separatingindividual metal slab sheets; wherein an air knife is directs an airflow onto the width of the metal slab before the unwound metal slab isfed through an align unit. The location of the air knife acting on themetal slab may be there where the metal slab is still on the metal slabcoil (and thus forms a part of the exterior of the metal slab coil) or,as an alternative, there where the metal slab is already unwound of themetal slab coil but at a location before the unwound metal slab coil isfed to a first align unit. The present transformation method of metalslab form coil figuration to sheet configuration enables to realise ahigher surface quality grade metal sheets. For further explanation andadditional advantages reference is made to the above clarification inrelation to the device according the present invention, which isincorporated here by reference in relation to the present transformationmethod as well.

The method may also comprise a method step E) stacking theindividualised metal slab sheets on at least one stack and/or the airflow may be directed onto the width of the metal slab. Furthermore anozzle directing the air knife onto the metal slab may be moved relativeto the rotatable coil holder to maintain a substantial constant distancebetween the nozzle and the metal slab before feeding it through an alignunit. To enhance the cleaning effect the air knife may be directed ontothe metal slab with a pulsating variable air speed. The air knife mayalso heat the air directed onto the metal slab and/or an additionalblow-drier may be used, for instance with an air temperature of 60-90°C.

The invention will be further elucidated herein below on the basis ofthe non-limitative exemplary embodiments shown in the following figures.Herein:

FIG. 1 shows a schematic side view on a device for transforming a metalslab from coil configuration into sheet configuration according theprior art;

FIGS. 2A and 2B show schematic two embodiments of a rotatable coilholder that is provided with an air knife according the presentinvention; and

FIGS. 3A and 3B show a third embodiments of a rotatable coil holder thatis provided with an air knife according the present invention in twodifferent positions.

In a metal slab transforming device 1 a metal slab in coil configuration2 is converted into metal slab sheets 3. A coil holder 4 that isrotatable according arrow P₁ holds the metal slab coil 2 from which themetal slab 5 is unwound according arrow P₂. After being unwound of themetal slab coil 2 the metal slab 5 is fed through a first align unit 6.After being aligned for a first time brushes 7 clean the metal slab 5after which brushes 7 a second align unit 8 acts on the unwound metalslab 5. The straightened metal slab is then cut into individual sheetsby a separator 9 to be stacked in a stacking unit 10. The rotatable coilholder 4, the align units 6, 8, the brushes 7, the separator 9 and thestacking unit 10 are placed in line. Some typical dimensions of a metalslab transforming device 1 are: thickness of the metal slab (gauge) 3-20mm, maximal width of the metal slab 2100 mm, maximum length of the metalslab 16 metres, maximum coil weight 36 tons, optional provision in theline of side trimmers, and metal slab yield strengths for example 1000MPa at 2000 mm width and 10 mm thickness.

FIG. 2A shows an embodiments of a rotatable coil holder 20, holding ametal slab coil 21 on the outside of which coil 21 an air knife 22 isacting. The air knife 22 is moveable in a radial direction (see P₃) tothe coil 21 and comprises two stops 23 that contact the outside of thecoil 21. A cylinder 24 urges a nozzle 25 towards the coil 21 so that thestops 23 a pressed against the coil 21. The nozzle 25 is connecting to agas feed 26. In FIG. 2B an air knife 27 is shown with a nozzle 28 thatis urged by springs 29 to metal slab 30 at a location where the metalslab 30 is already unwound of coil 31.

FIGS. 3A and 3B show an air knife 40 that is carried by a rotatable arm41. In FIG. 3A a coil 42 is relatively large while in FIG. 3B the coil42 is unwound for a substantial part so that the remaining coil part 43has a substantial smaller diameter than the coil 42 as depicted in FIG.3A. The arm 41 is connected to a weight 43 That urges the air knife 40against the coil 42. Furthermore is shown that the air knife 40 connectsvia a hose 44 and a pipe 45 to a fan assembly 46. Above the air knife 40also a blow-drier 47 is attached to the arm 41 to further enhancedcleaning.

1. A device for transforming a metal slab from coil configuration intosheet configuration, comprising: a rotatable coil holder, at least onealign unit; and a separator; wherein the rotatable coil holder, the atleast one align unit and the separator are placed in line, wherein therotatable coil holder is provided with at least one air knife thatdirects an air flow onto the width of the metal slab.
 2. The deviceaccording to claim 1, wherein the device also comprises a stacking unitplaced in line with the a rotatable coil holder, the least one alignunit, and the separator.
 3. The device according to claim 1, wherein theair knife is comprising an air feed and a nozzle with a width of atleast the width of the metal slab coil to be transformed.
 4. The deviceaccording to claim 1, wherein the air knife is provided with at leastone air heater.
 5. The device according to claim 1, wherein a nozzle ofthe air knife is mounted on a nozzle carrier that is moveable relativeto the rotatable coil holder.
 6. The device according to claim 5,wherein the nozzle carrier is provided with bias means and at least onestop directed towards the rotatable coil holder to contact the outsideof the metal slab coil.
 7. The device according to claim 5, wherein thenozzle carrier is pivotable connected to the rotatable coil holder. 8.The device according to claim 7, wherein the pivotable nozzle carrier isprovided with a balance weight to urge the nozzle with a constantpressure against the outside of the metal slab coil.
 9. The deviceaccording to claim 1, wherein parallel to the air knife a subsidiary airblower is situated, which subsidiary air blower comprises at least oneair blower fan, an air blower feed and an air blower nozzle with a wideof at least the width of the metal slab coil to be transformed.
 10. Thedevice according to claim 1, wherein the air knife is provided with atleast one inlet for the extraction of air.
 11. A method for transforminga metal slab from coil configuration into sheet configuration,comprising the method steps: A) placing a metal slab coil on a rotatablecoil holder, B) rotating the metal slab coil and unwinding the coil; C)feeding the unwound metal slab through at least one at align unit; andD) separating individual metal slab sheets; wherein an air knife isdirects an air flow onto the width of the metal slab before the unwoundmetal slab is fed through an align unit.
 12. The method according toclaim 11, wherein the method also comprises the method step E) stackingthe individualised metal slab sheets on at least one stack.
 13. Themethod according to claim 11, wherein the air flow directed onto thewidth of the metal slab is heated.
 14. The method according to claim 11,wherein a nozzle directing the air knife onto the metal slab is movedrelative to the rotatable coil holder to maintain a substantial constantdistance between the nozzle and the metal slab before feeding it throughan align unit.
 15. The method according to claim 11, wherein the airknife is directed onto the metal slab with a pulsating variable airspeed.